The n-fuse one uses the pico gateway protocol and can safely be used with USB.
For other devices, don’t attempt to use USB. LoRaWAN is timing critical and timing for USB connected concentrators is less precise.
I know you don’t want to have an additional device but for SPI the easiest way to go is a Raspberry Pi. It does not have to have a keyboard and monitor attached, network access is all that is required. I have serveral RPis deployed in metal casings, outside with just a network connection. I rarely need to log on. (There is one I haven’t logged on to for > 2 years that is still running fine)